In general, a cutting tool is configured of a cutting tip including an abrasive, directly performing a cutting operation, and a body (core) to which the cutting tip is provided to be fixed.
The body is generally disk shaped, in another embodiment, may be formed in a linear form such as a frame gang saw.
Ordinarily a frame gang saw has been widely used for cutting a workpiece, for example, a large-sized block of concrete, marble, granite, sandstone, limestone, or the like, into a plurality of thin slabs.
As a method of using a frame gang saw there maybe provided a method of using a frame gang saw by spraying an abrasive such as a grain form steel shot and a method of using a frame gang saw by way of a cutting tip including an abrasive fixed to a body thereof.
In the frame gang saw, a frame is fitted with a linear form body, in which linearity may be maintained by applying tension to the body.
In addition to the frame gang saw used for the cutting of a large-sized workpiece, a large sized circular saw blade, a wire saw, a band saw, or the like may be used.
The large sized circular saw blade is in the form of a disk to perform a stabilized cutting operation at a rapid cutting speed and is configured to include multiple bodies so as to cut several sheets or plates at a time. Meanwhile, in the case that a workpiece has a relatively large thickness, and thus a diameter of the body in the disk form saw is relatively great, the thickness of the body of the saw blade should be increased and an overall system should have a relatively large volume in order to realize stabilization of the body of the saw blade. That is, there may be increased cutting loss of relatively expensive material during the cutting work on a workpiece.
Generally, a wire saw is used at the time of mining stone, but recently the wire saw has been under development for use in cutting quarried stone into a plurality of slabs.
However, to date, in the case of the wire saw, a high unit-price in the production therefor and a large amount of cutting loss at the time of cutting a workpiece are increased.
In the case of frame gang saw, a body (hereinafter, referred to as ‘blade’) may penetrate into the inside of the workpiece while performing a cutting operation without a limitation with regard to the height of workpiece. That is, the frame gang saw is widely used for cutting a large-sized block of stone into a plurality of slabs.
However, since unlike other cutting methods, the frame gang saw performs a cutting operation through a method of performing a cutting operation using reciprocal movement therein; for example, when the cutting operation is performed using a cutting tip provided to include abrasive grains such as diamond particles or the like, a tail supporting the abrasive grains is not formed, thus causing abrasive grains to be detached therefrom in early stage. The method of using a cutting tip fitted with the body is generally used in cutting marble having a comparatively low hardness, and, in a case of cutting granite or the like, a method of performing a cutting operation by spraying an abrasive such as a steel shot in the form of a grain together with water thereto is principally used.
The frame gang saw is universally configured as a reciprocating multiplane type, for example, having about 250 blades, of in which each blade may have a length of 3 m or more, a thickness of 2 mm to 5 mm, and a height of 50 mm to 200 mm.
A block of granite or marble is cut into a plurality of slabs using a frame gang saw and the slabs are then polished to be completed as products such as tiles or blocks.
In the case of a deviation in the thickness of slabs, when a deviation in the thickness of a slab is less than 1.5 mm, the slab may be regarded as being sufficiently flat, while, in a case in which a deviation in the thickness of a slab is greater than about 2 mm, the slab is not polishing-processed but generally scrap-processed.
In order to satisfy the above-mentioned conditions demanded for the quality of final granite or marble products, a blade should not be deviated from a vertical path in which a block of granite or marble is cut in the cutting operation. The deviation of a blade from a cutting path may occur when force is locally applied to the blade to thus cause the blade to be distorted or bent, from which the deviation from the cutting path may occur from a linear path, leading to an excess in an allowable level of thickness deviation in slabs.
Deformation of the blade may bring about permanent wear of blade due to buckling and breakage.
One factor generating local force, from which a deviation of a blade from a cutting path may occur, maybe an uneven surface state, namely, a non-uniform thickness, in a workpiece block.
Quarried large stone block may have defects in the interior thereof.
Defects may appear on the surface of a workpiece, from an external impact or drilling process while mining stone.
As the gang saw blade is used in cutting a quarried workpiece, a large stone block, the blade may experience a relatively high force of change due to the non-uniformity in materials, thus resulting in a local abrasion on a steel blade to be then finally deviated therefor from a cutting path.
In an initial cutting operation of the gang saw blade, the blade goes downwards, toward the workpiece, in order to cut the workpiece, and then, only a portion of the blade may be in contact with the block of stone, the workpiece, and in particular, in the case of using multiple blades, only a portion of the blades may be in contact with the stone block in certain regions thereof. That is, the above-mentioned defects may occur on the blades.
Even in the case of one blade, a surface shape of the workpiece in contact with the blade may be different, depending upon respective positions thereof contacting the blade, from which a impact applied from the workpiece to the blade or deflection of the blade is uneven, such that a groove formed in the workpiece in the initial cutting operation may not be formed in a suitable position.
Particularly, a workpiece may be relatively long, for example, 2 m to 4 m in length, such that the workpiece may have a similarly sinuous and locally wide groove formed therein.
Since a blade receives tension stress on both surfaces thereof; when the blade is used to perform the cutting operation in such a manner that the blade is constrained in a groove formed in an abnormal position, as described above, even in the case in which the extent of the unevenness on the surface of the workpiece is not serious, a linear groove can be formed when cutting has been undertaken up to a certain depth level.
However, due to a serious indentation state or unevenness on the surface of a workpiece or on the inside thereof or due to an unstable cutting operation in the cutting system, the blade thereof may be greatly deviated from an original cutting position, thus causing the blade to be broken and thus damaged.
In addition, even in the case that breakage of the blade does not occur, since a linear groove cannot be formed therein, the thickness of slabs may exceed an allowable thickness and thus the slabs may be scrap-processed.
In order to reduce defects, during initial work, a descent speed of blade is relatively slow in order to reduce the extent of load applied to the blade, and when the blades in contact with the workpiece have entered the interior of the stone block to a proper depth level to allow all blades to come in contact with the stone block, that is, when all of the blades are in contact with the workpiece, the speed of the cutting operation is gradually increased up to a normal cutting speed.
However, the initial cutting operation is time consuming, and furthermore, an uneven load may be applied to the blades.
In addition to a peculiar defect of a workpiece, a technical defect may also occur in a cutting system as well as serious mechanical wear, producing defective products when cutting the workpiece such as granite or the like into a plurality of slabs, leading to highly priced products.
Therefore, an improved method or system for cutting a workpiece such as granite, marble, or rock into slabs is required.